calculate the following pmf and cdf using the given probability distribution: x -10 -5 0 10 18 100 f(x) 0.01 0.2 0.28 0.3 0.8 1.00 a) p(x < 0) b) p(x ≤ 0) c) p(x > 0) d) p(x ≥ 0) e) p(x